roofing a dormer

As part of our remodel we raised our peaked entry way. The result is a dormer style roof that meets the main roof. My question is regarding the sequence for the roof installation, especially regarding the small triangular shaped section under the dormer roof eve where the dormer roof meets the main roof.

1) should the shingles of the main roof be pulled back, then the plywood of the entry gable installed to contact the plywood of the main roof (along the valley line), all before installing any new roofing material, or
2) does the main roof get finished to where the entry walls come up through the main roof, then the plywood installed on the entry cable such that the plywood sits on the roofing material of the main roof (along the lower part of the valley formed by the dormer eve)? All followed by the valley flashing.

Thanks to Ed's comments in a previous post, I believe I have the valley flashing and everything else figured out. That small triangel area has me puzzled. Also I will be sealing the wall in that hard to reach section with the ice / water seal, flashing, felt, and stucco prior to setting the last piece of entry roof plywood.

roofing a dormer

roofing a dormer

Ed-
See attached pics.

What is the proper sequence of installation to get the roofing along the main roof to the wall coming up through the roof (especially into that small corner under the eve) as well as into the lower part of the valley formed by the gable roof eve. Note that the gable roof decking piece that makes the eve is just tacked on and easily removable to roof, flash and stucco the wall.

Oh and try to keep the laughter to a minimum regarding the gutter installation......left over from the old roof line and obviously there is some work to be done there. Also the paper in the pic is part of the temp cover and I know it need to run horizontally.

roofing a dormer

First, remove the bottom row of plywood decking on both sides of the new dormer.

Second, remove the shingles that abutt the side wall of the dormer including the courses which go up to and slightly past the nottom of the valley..

Third, Install at least an 12" wide strip of Grace Ice and Water Shield splitting the differnce with 6" on the main house roof deck and the other 6" going up the walls of the dormer sides.

Fourth, Install the shingle along the bottom below the shingles if need be. Have a piece of Apron Roof To Wall Angled sheet metal counter flashing fabricated or bought at the roofing supply house nearby, and allow it to span at least 3" past both sides of the walls on the left and the right. Take your tin snips and trim the bottom of those 3" + pieces that go past the corners. Cut the bottum on an appropriate angle so that the sheet metal flaps can make the bend around the corners without being inhibited by the slope of the decking on the main house roof. Bend them and nail them to the side walls.

Fifth, when installing the new shingles, secure on 5" baby tin step flashing for each successive course of shingles. The bottom of the baby tin flashing should line up with the bottom of the shingle.

Do all of the shingling under the new dormers soffit overhangs before replacing the bottom row of plywood decking. Then reinstall the decking.

Install the felt paper and the gutter apron drip edge metal flashing and the gable sides overhanging drip edge flashings and then it is ready to be shingled.

Now shingle the dormer and make sure the shingles from the dormer go past the center of the valley at least 12" and do not nail the shingles any where near the middle of the valley.

Maybe I will add more with an edit after looking at the photos again.

You also need to tear off the shingles from the main house roof where it meets the dormer valleys.

Prior to installing the felt paper and the new shingles, make sure that you also install a 3 foot wide piece of Grace Ice and Water Shield in the valley and overlap the top of the valleys so there is no unprotected spots remaining.

The main house roofs shingles will be the ones that go on top of the shingles which passed the center of the valley and then these will need to be trimmed. Snap a chalk line in the valley. At the bottom of the valley, go 2" away from the center of the valley and line up the chalk line 1" away from the center of the valley for the top measurement.

roofing a dormer

One of the problems you're having is that you didn't set out the end points on the main roof where the gable roof joists were to hit the roof. From what I see, you wanted a valley on either side of the gable. The first thing to have done was lay 1x8's or 10's down on the roof flat to the eaves in the shape of an "^". The ridge board would hit the top of the ^ and all the gable rafters would be sitting on the 1x's from the top to the eaves. This guarantees a straight, continuous valley on both sides. This requires you to cut compound angle cuts on the bottoms of the joists, where it hits the roof. These need to sit dead flat on these boards for this to be a structurally sound addition.
This is a structure with alot of angle cuts that need to meet up with another piece of wood. From what I see, you need the help of someone with framing experience who can "see " the finished product. This sort looks like someone winging it. Not a good idea.
Ron

roofing a dormer

Ed-
thanks so much for the reply. That's what I was looking for. I already picked up the roll of ice/water shield (surprised at the $$). I think I got it all, and it makes sense.

Another question, the pics show the last sheet of dormer plywood sitting on the main roof decking. It seems that this angle should be cut such that the decking doesn't actually sit right on the main roof shingles. True or does it not matter that much since the valley will cover the decking and extend a bit over the edge such that the edge of the dormer decking it completely up underneath the valley?

roofing a dormer

Ron
Thanks for the input. I'm not sure I completely visualize what you're saying, but......

this is part of a complete interior remodel. We have re-framed just about every wall in the house. The framing is the only thing we hire out. The framing crew we had has a very strong reputation and has worked with one of the top custom home builders in the Bay Area.....maybe more info than required. Anyway..... there is a gable roof ridge beam that runs to the gable "V". The are flat 2x's that run along the valleys. The valleys are actually "straighter" than how they look in the picture.

You mention the main roof point don't line up with where the gable roof rafters hit the main roof. The valley used to end where the last gable rafter hit the main roof. After everything was framed there was a need to cut the gable roof rafters back (the way they were "didn't look right" according to the interior designer (wife)). So when the rafters were cut back that moved the point where the edge of the gable roof meets the main roof farther up the main roof. The way the roof angles lay out, there is not enough room to get another gable rafter in from the wall to the point where the gable roof meets the main roof.

The stucture is quite sound. Maybe a few more pic might help illustrate what was done.

Please understand I'm not trying to dismiss what you are saying, quite the opposite. I want to understand if there are any shortcomings and get them fixed, but I'm not sure I've clearly communicated everything that has been done. I will post up more pics

roofing a dormer

The picture I see has the last lighter colored ply at a different angle hitting the roof then the ply further up the valley.
If your plan was to have a wall coming up rather then the gable dormer hitting the roof line all the way down to the eaves, you can ignore that part of the post.
To flash this properly you would need to install step flashing where the old roof hits the gable wall. The framers should have cut back the roof shingles about a 1/4" away from the wall so the flashing could get set. You slide the flashing up under the shingle so it doesn't stick out and nail it to the wall(one nail, at the top). Work your way up the shingle row until you get to the top row.
Ron

roofing a dormer

Quote:

Originally Posted by steve1234

Another question, the pics show the last sheet of dormer plywood sitting on the main roof decking. It seems that this angle should be cut such that the decking doesn't actually sit right on the main roof shingles. True or does it not matter that much since the valley will cover the decking and extend a bit over the edge such that the edge of the dormer decking it completely up underneath the valley?

Again, Ed, thanks for the info......

That needs to be as tight to the main house decking as possible.

That is why you have to remove the shingles on the main house roof for about 3 feet away from the valley.

Then you shingle the dormer roof and then the main house roof over the dormer shingles.

roofing a dormer

Ed the roofer said:
"You woud be well served for cosmetic and funstional purposes to re-cut your valley decking so that it is a straight line from top to bottom, without a hook in it."
Unfortuneately you can't just cut the ply. When you do, the plywood will be about 6" off the roof if you continue the present angle down. The initial "V" angle installed on the roof is not compatible with the roof pitch(too low). To fix this you would need to repitch(increase) the roof or increase the "V" angle.
That's why this statement by the OP didn't make sense:
"The framing crew we had has a very strong reputation and has worked with one of the top custom home builders in the Bay Area."
This looks like a homeowner installed handywork, not professionals that do it for a living. There is a direct relationship between the roof pitch and the intersecting gable angle. If they're not in sync, you get the pictured result.
Ron